Installation guide

Release Notes
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11.6. Virtualization
Virtualization Guide
The Virtualization Guide
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details the process to install, configure and manage the virtualization
technologies in Red Hat Enterprise Linux 6.
12. Kernel
12.1. Resource Control
12.1.1. Control Groups
Control groups are a new feature of the Linux kernel in Red Hat Enterprise Linux 6. Each control
group is a set of tasks on a system that have been grouped together to better manage their interaction
with system hardware. Control groups can be tracked to monitor the system resources that they use.
Additionally, system administrators can use control group infrastructure to allow or to deny specific
control groups access to system resources such as memory, CPUs (or groups of CPUs), networking, I/
O, or the scheduler. Management of control groups in userspace is provided by libcgroup, enabling
system administrators to create new control groups, start new processes in a specific control group
and set control group parameters.
Note
Control Groups and other resource management features are discussed in detail in the Red Hat
Enterprise Linux 6 Resource Management Guide
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12.2. Scalability
12.2.1. Completely Fair Scheduler (CFS)
A process (or task) scheduler is a specific kernel subsystem that is responsible for assigning the order
in which processes are sent to the CPU. The kernel (version 2.6.32) shipped in Red Hat Enterprise
Linux 6 replaces the O(1) scheduler with the new Completely Fair Scheduler (CFS). The
CFS implements the fair queuing scheduling algorithm.
12.2.2. Virtual Memory Pageout Scalability
Implemented by the kernel, virtual memory presents applications with a single, contiguous block of
memory addresses. The reality underlying this presentation is complex, with actual physical addresses
commonly fragmented and even paged out to much slower devices such as fixed disks. The virtual
memory addresses are organized by the kernel into standard units called pages. The kernel in
Red Hat Enterprise Linux 6 features enhanced management of virtual memory pages, reducing the
processing load required on systems with large amounts of physical memory.
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http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/index.html
47
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/index.html